The invention relates to a grid welding machine operating on the electrical resistance welding principle and having continuous forward feed of the longitudinal wires. Groups of rotary electrodes and counter-electrodes co-operate in pairs and are arranged above and below the feed path of the longitudinal wires, respectively. The feed path for the cross-wires has an end section which is curved coaxially with the axis of rotation of the groups of electrodes, and which opens out generally tangentially into the feed path of the longitudinal wires. Such a machine is hereinafter described as "of the kind hereinbefore described."
In the case of a grid welding machine of this species, known from the West German DAS No. 1 108 354, block-shaped welding electrodes and counter-electrodes are arranged in rows along the generatrices of cylindrical drums having parallel axes, and the drum carrying the active electrodes contains inside it the welding transformers connected to the electrodes, whilst the counter-electrodes are formed on the other drum as spring-mounted passive current-bridges. With each individual row of active electrodes a cross-wire holder is associated, and on the drum carrying the active electrodes cross-wire reels are mounted, to rotate with it, and also picker-gear which during the rotation of the drum pulls wire off the reels and delivers it into the cross-wire holders. The cross-wires delivered to the holders are cut to length by means of shears rotating with the holders and then carried by the holders, into alignment with the associated rows of electrodes along a curved feed path which in the welding region opens out tangentially into, and in the direction of the feed path of the longitudinal wires.
This known machine has a relatively complicated and space-wasting construction and it includes relatively large moving masses since with each row of electrodes its own cross-wire reel must be associated. In order to keep the moving masses within acceptable limits, the reels must be made relatively small, which on the other hand demands frequent exchange of empty reels for full ones and therefore frequent stopping of the machine. Again, the known machine does not enable the pitch between the cross-wires to be altered.